Known is a method for producing vacuum in a vacuum fractionating column for distilling oil stock (black oil) by pumping a gas-vapor medium with the help of a multi-stage vapor ejector pump which is fed with water steam as a high-pressure gas from an external source (see U.S. Pat. No. 2,105,935 A1, IPC B01D 3/14, Jan. 18, 1938).
A plant for producing vacuum in a vacuum fractionating column for distilling oil stock is known from said patent, said plant comprising a pipe for drawing a gas-vapor medium off from the vacuum column, a condenser and a multi-stage vapor ejector pump, said multi-stage vapor ejector pump at its high-pressure gas inlet of the first compression stage being connected to an external source of water steam, and at its gas-vapor mixture outlet being connected to an inlet of a second compression stage.
The disadvantages of the prior art method and plant are use of the external source of water steam and drawing off the water steam condensate in the mixture with oil fractions out of the plant, said disadvantages resulting in environmental pollution and loss of the distillate.
The additional disadvantage is large power inputs associated with using a large quantity of steam and water for organization of the multi-stage process for compressing the gas-vapor medium and condensing vapor.
The closest prior art to the invention in part of the method as a subject-matter of the invention, in the technical essence and in the accomplished result is a method for producing vacuum in a vacuum column for distilling crude oil, said method comprising: pumping a gas-vapor medium out of the vacuum column by a gas-gas ejector by feeding a high-pressure gas thereto to generate a gas-vapor mixture at an outlet thereof with a pressure higher than that of the gas-vapor medium at an inlet thereto; feeding the gas-vapor mixture into a condenser followed by cooling thereof and generating a gas mixture and a vapor phase condensate; feeding the gas mixture and the high-pressure gas into a second gas-gas ejector to generate a gas-vapor mixture at an outlet thereof with a pressure higher than that of the gas mixture at an inlet thereto; feeding the gas-vapor mixture from the second gas-gas ejector into a second condenser followed by cooling thereof and generating a gas mixture and a vapor phase condensate at an outlet of the second condenser; and discharging the gas mixture out of the second condenser for a designated purpose (see U.S. Pat. No. 7,267,747, IPC B01D 3/10, Sep. 11, 2007).
The closest prior art to the invention in part of the apparatus as a subject-matter of the invention, in the technical essence and in the accomplished result is a plant for producing vacuum in a vacuum column for distilling an oil feed, said plant comprising: a pipeline for discharging a gas-vapor medium out of the vacuum column for distilling the oil feed; a gas-gas ejector; a condenser; a second gas-gas ejector; and a second condenser, wherein said gas-gas ejector is connected, at its low-pressure gas inlet, to the pipeline for discharging the gas-vapor medium out the vacuum column for distilling the oil feed and, at its gas-vapor mixture outlet, is connected to an inlet of the condenser that has a condensate outlet and a gas mixture outlet being connected to a gas mixture inlet of the second gas-gas ejector, said second gas-gas ejector is connected, at its gas-vapor inlet, to the second condenser that has its condensate inlet and gas mixture outlet (see U.S. Pat. No. 7,267,747, IPC B01D 3/10, Sep. 11, 2007).
The disadvantages of said method for producing vacuum in a vacuum column for distilling an oil feed (in particular, oil residue) and said plant for carrying out the same are large power inputs associated with using a large amount of water steam and water for organization of the multi-stage process of compressing the gas-vapor medium and inter-stage condensing the vapor. The use of an external source of water steam and discharge of the water steam condensate in mixture with oil fractions out of the plant are the disadvantages as well, said disadvantages resulting in environmental pollution and loss of the distillate.